| 摘要 |
A plug-in timer has a set of input terminals and a set of output terminals as well as a contactor operable to make and/or break electrical connection between these sets of terminals in accordance with a pre-setable 24 hour program. The timer is powered from a small built-in battery, and comprises its own quartz clock and programming-and-control means. The contactor is actuated by a miniature DC motor through a gear and cam arrangement. The operation of the DC motor is controlled by the programming-and-control means, which provides power from the battery to the motor in accordance with a pre-set program; which pre-set program may be modified at any time by way of a keyboard and a numeric display means. The contactor operates by way of hard metal contacts and very little power dissipation occurs within the timer. The timer can be plugged into a special wall switch receptacle and then operates to programmably control the flow of power to the load controlled by this wall switch. Since the timer has its own built-in source of energy and clock, its operation is totally independent of the power line, and it will therefore not be affected by a power failure. With a usage rate of two CONNECT-actuations and two DISCONNECT-actuations per day, plus occasional over-rides, the battery will last for years before needing replacement.
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